Section 3 General Corrosion

**Chapter 5**

**Abstract**

**1. Introduction**

**1.1 Acids**

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their effect on other substances.

**1.2 Factors affecting acidic strength**

Theory

The Arrhenius Acid and Base

Swedish Svante Arrhenius, in 1884 proposed the concept of acid and base based on the theory of ionization. According to Arrhenius, the acids are the hydrogencontaining compounds which give H<sup>+</sup> ions or protons on dissociation in water and bases are the hydroxide compounds which give OH ions on dissociation in water. This concept is only applicable to those compounds which dissolved in aqueous solution (or you can say where water is the solvent). It covers many common acids, bases and their chemical reactions, but there are also other compounds that have the characteristics of acids and bases but they do not fit into Arrhenius concept.

**Keywords:** acids and bases, Arrhenius acid-base theory, the water-ion system,

Several scientists put various definitions to characterize the acids and bases in which some of the concepts are quite narrow and some are comprehensive. Acids and bases are existing everywhere in our daily life. Every liquid except water, that we used having acid and basic properties, for example, vinegar (contains acetic acid), soft drinks (contains carbonic acid), buttermilk (contains lactic acid), soap (contains base). The earliest definitions were made on the basis of their taste and

The concept of acids and bases have been defined many times in different ways.

Acid are those substances which have sour in taste, sharp odor, corrosive, having pH < 7 and turn blue litmus red. The neutralization reaction occurs when acid reacts with alkali, forms salt and water. The products are less acidic or basic than reactants. It reacts with metals, produces H2. For example, the reaction between sodium hydroxide (base) and hydrochloric acid, forms sodium chloride (salt) and water.

The strength of acids and bases depends on following factors:

amphoteric nature of water, hydrogen or hydronium ion

*Shikha Munjal and Aakash Singh*

#### **Chapter 5**
